Such a surgical stapling instrument is known from WO 01/91646 A1. WO 01/91646 A1 discloses a surgical stapling instrument having a staple fastening assembly located in the distal end region of the stapling instrument, a shaft, and a handle extending from the shaft in the proximal end region of the stapling instrument. The staple fastening assembly includes a curved cartridge device, which comprises several curved open rows of staples having a concave side and a convex side. A curved anvil is arranged opposite to the cartridge device. The anvil has a staple forming face and is adapted to cooperate with the cartridge device for forming the ends of the staples exiting from the cartridge device. The anvil can be moved relatively with respect to the cartridge device from a spaced position for positioning tissue therebetween to a closed position for clamping the tissue. Moreover, a knife is contained in the cartridge device and is positioned on the concave side of at least one row of staples.
The surgical stapling instrument disclosed in WO 01/91646 A1 can be used to excise tissue, e.g. polyps, and to stop bleeding virtually immediately. In a surgical procedure, the stapling instrument is introduced, e.g., into the anal canal and moved to the site of the tissue to be resected. The tissue to be excised can be pulled into the area between the anvil and the cartridge device, when the cartridge device and the anvil are in a spaced or open position, by means of a separate gripping instrument. Afterwards, the cartridge device is moved relatively with respect to the anvil in order to clamp the tissue. When the cartridge device and the anvil have reached the closed position, the surgeon can “fire” the instrument, which means that the staples are driven out of the cartridge device, penetrate the tissue, whereupon the ends are bent by the anvil, and the knife is moved towards the anvil in order to cut the tissue. When the instrument is retracted, the completely excised tissue stays in the staple fastening assembly and can thus be safely removed from the patient's body.
A particular advantage of the surgical stapling instrument disclosed in WO 01/91646 A1 is the shape of the staple fastening assembly in which the cartridge device and the anvil have a generally arc-like shape in a cross-sectional plane. This allows for unobstructed view and access towards the concave inner faces of the cartridge device and of the anvil.
In the surgical stapling instruments known from WO 01/91646 A1, the anvil is supported by means of an arm extending from an end of the anvil and generally running in parallel to the direction of relative movement of the anvil with respect to the cartridge device. The other end of the anvil is not supported. Thus, under load when the tissue to be resected is clamped, the anvil might distort, leading to a misalignment of the ends of the staples and the staple forming face of the anvil. For small surgical stapling instruments designed to be inserted through a small-diameter channel, this is a particular problem as there is not space enough for a sufficiently dimensioned, strong support arm at the end of the anvil.
In order to overcome this drawback, it has been proposed to use a retaining pin, which does not impede the free access to the space between the anvil and the cartridge device, but which is moved, after clamping the tissue, between the cartridge device and the anvil in order to align the cartridge device and the anvil. Such retaining pin is disclosed in PCT/EP03/06352. The retaining pin is located close to the free end of the anvil/cartridge device. In the cases when the length of the tissue to be excised is less than the arc length of the device, the known retaining pins do not cause risks of unwanted piercing of tissue.
It is possible, however, that tissue to be excised is longer than the arc length of the device. In those cases the stapling instrument must be applied more than once, substituting the spent staple cartridge with a loaded one. The problem of current stapling instruments with a retaining pin at the free end of the cartridge device is that their retaining pin leaves a hole in the tissue outside the excision line defined by the knife length.
It is the object of the invention to improve the clinical benefits of a surgical stapling instrument as generally known from WO 01/91646 A1, without jeopardizing its technical performance.
This problem is solved by a surgical stapling instrument having the features of claim 1. Advantageous versions of the invention follow from the dependent claims.
The surgical stapling instrument according to the invention comprises a staple fastening assembly including a curved cartridge device and, opposite to the cartridge device, a curved anvil. The cartridge device comprises at least one curved open row of staples having a first end and a second end and having a concave side and a convex side. The anvil has a staple forming face and is adapted to cooperate with the cartridge device for forming the ends of the staples exiting from the cartridge device. Moreover, a moving device is adapted to move the anvil relatively with respect to the cartridge device, essentially in parallel relationship, from a spaced position for positioning tissue therebetween to a closed position for clamping the tissue. A staple driving device is adapted to drive the staples out of the cartridge device towards the anvil. In the cartridge device, there is contained a knife having a first side and a second side opposite to the first side. The knife is positioned on the concave side of at least one row of staples, the first side of the knife facing to said row of staples. A knife actuating device is adapted to move the knife towards the anvil. According to the invention, the staple fastening assembly comprises a retaining pin adapted to move between the cartridge device and the anvil to align the cartridge device and the anvil. The retaining pin is located on the second side of the knife in an intermediate region between the first end and the second end of the curved row of staples.
In other words, the retaining pin is not located at an end of the curved row of staples, but it is situated in an area where tissue which might be penetrated by the retaining pin upon movement of the retaining pin will be excised when the knife is actuated. Consequently, there is no risk that healthy tissue or tissue remaining in the patient's body will be injured by the retaining pin. The importance of the position of the retaining pin will be better understood by means of the description of an embodiment of the invention following further below.
Preferably, the stapling instrument according to the invention comprises a shaft device and a handle, the staple fastening assembly being located in the distal end region of the stapling instrument and the handle extending from the shaft device in the proximal end region of the stapling instrument. In a preferred version of the invention, the staple fastening assembly is removably mounted in the distal end region of the shaft device. In this way, the shaft device, which can include many components of the moving device, the staple driving device, the knife actuating device and members used to move the retaining pin, can be designed as a single-patient reloadable device, whereas the staple fastening assembly can be designed as a single-fire disposable article which is replaced after its staples have been delivered. Preferably, the movement of the retaining pin is actuatable via an actuating member located at the handle. In a preferred embodiment, the direction of movement of the retaining pin is essentially in parallel to the direction of relative movement of the anvil with respect to the cartridge device.
The staple forming face of the anvil can be generally planar, but other shapes, e.g. an undulated shape, are conceivable as well.
In an advantageous version of the invention, the staple fastening assembly is adapted to allow unobstructed access towards concave inner faces of the cartridge device and of the anvil. Such design, which is generally known from WO 01/91646 A1, largely facilitates the handling of the stapling instrument in a surgical procedure.
Preferably, the cartridge device and the anvil have a generally arc-like shape in a cross-sectional plane, the arc extending over an angle in the range 10° to 350°.
In a preferred version of the invention, the anvil is supported by means of an arm extending from an end of the anvil and generally running in parallel to the direction of relative movement of the anvil with respect to the cartridge device. This kind of support allows for a large unobstructed area between the cartridge device and the anvil but has the general disadvantage that it is less rigid than, e.g., a design using a support arm in the center of the cartridge device and the anvil or using more than one support arm. However, this disadvantage is compensated by the presence of the retaining pin by means of which the cartridge device and the anvil are aligned during the steps of the procedure when an alignment is critical, i.e. in particular when the cartridge device and the anvil are moved toward one another to force the tissue to compress to a thickness such to be stapled across and when the staples are then “fired” from the cartridge device and are formed by grooves in the staple forming face of the anvil.
Preferably, the distance between the cartridge device and the anvil in the closed position is adjustable. For example, the moving device can comprise an adjustable stop in order to prevent the cartridge device (or anvil) from moving beyond the stop position and from clamping the tissue too much. Or a series of cartridge devices with different built-in tissue stops can be used according to the tissue thickness. It is also conceivable to use a series of cartridge devices which have different longitudinal dimensions which are adapted to the desired distance between the cartridge device and the anvil in the closed position. By adjusting the distance between the cartridge device and the anvil in the closed position, the instrument can be matched to the thickness and type of tissue to be stapled and excised.
In an advantageous version of the surgical stapling instrument, the cartridge device comprises a replaceable cartridge containing staples. In this way, a used cartridge without staples can be replaced with a fresh one, if required. This is particularly beneficial when the instrument is to be used several times during the same surgical procedure.
Some of the features discussed above are already known from WO 01/91646 A1, in particular an arc-like shape of the cartridge device and the anvil and a support arm extending from an end of the anvil, which enables an easy access to the site of surgery, e.g., for endoscopic optics or additional surgical instruments. The retaining pin of the present invention allows for a greater precision of the surgery without involving the risk of injury to tissue that may not be removed from the patient in the form of a specimen.
Herein, the term “staple” is used in a very general sense. It includes metal staples or clips, but also surgical fasteners made of synthetic material and similar fasteners. Synthetic fasteners usually have a counterpart (retainer member) held at the anvil. In this sense, the terms “anvil” and “staple forming face” also have a broad meaning which includes, in the case of two-part synthetic fasteners, the anvil-like tool and its face where the retainer members are held, and similar devices.
Generally, the stapling instrument according to the invention can be used in all kinds of surgery disclosed in WO 01/91646 A1, which is incorporated by reference herein.